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Carrie Underwood is opening up about how hard it's been "bouncing back" after giving birth to her second child.

The 36-year-old country star, who welcomed son Jacob with hubby Mike Fisher on Jan. 21, shared an Instagram photo of herself working out on Tuesday. In her caption, she got candid about her struggle to get back into shape.

"I’m going to be honest, 'bouncing back' after having Jacob has been much more difficult than after I had Isaiah and I’ve been pretty hard on myself lately. I go into the gym and I can’t run as fast or as far. I can’t lift as much weight or do as many reps as I could a year ago," the former "American Idol" champ wrote in the caption.

"I just want to feel like myself again," she continued, "for my body to feel the way that I know it can."

The "Champion" singer said for nearly a year, she's felt her body belonged more to baby Jacob than herself.

"As I was working out today, I realized that for the past 11(ish) months, my body has not belonged to me. It was a perfect home for Jacob. And even now it belongs to him every time he drinks his milk," she wrote.

The Grammy winner, whose older son, Isaiah, turned 4 in February, said from now on she'd focus on the positives.

"As I prepare for red carpets and for life on tour, right now I make a promise to myself to start appreciating what my body CAN do and stop focusing on what it can’t," she wrote. "I promise to stop analyzing every angle and every curve and every pound and every meal."

Underwood knows embracing her body will take time — so she vowed to take it "day by day."

"I’m going to keep staying the path because it is a journey and as long as I’m always working towards my goals, one day I’ll reach them," she wrote.

In the meantime, she promised to continue to "smile at the girl in the mirror, and work out because I love this body and all it has done and will continue to do!"